1. Field of the Invention
The present invention relates to printers and, more specifically, replaceable print rollers for printers.
2. Description of the Related Art
Many types of printers include a roll of material that is used in the printing process. A typical example includes a roll of printing paper, upon which information may be printed. The paper is wound in a continuous sheet on a supporting core, and the core is mounted on a spindle in the printer. In another example, thermal printers utilize thermal transfer ribbon wound on a core. The thermal transfer ribbon is thermally activated during printing.
When the printing paper or ribbon is depleted, the empty core is removed from the spindle and replaced with a fully wound core, thereby returning the printer to service. The core typically includes features for accurately retaining the core on the spindle, in proper axial alignment with the printing mechanism, and in proper circumferential alignment around the spindle. Known printers that utilize cores retained on a spindle are referred to in U.S. Pat. Nos. 5,833,377; 5,947,618; 6,425,551; 6,609,677; and 6,609,678, and U.S. patent application Ser. Nos. 2003/0080238 and 2003/0106957, the entire disclosures of which are incorporated herein by reference.
In one known design, the spindle includes three slots disposed axially around the perimeter. The slots receive corresponding straight axial splines projecting inwardly along the inner surface or bore of the core. The core may be inserted axially over the spindle by engaging the corresponding splines and slots, with the splines providing circumferential retention around the spindle to prevent slippage.
Additional features are required for locking the core in axial position over the spindle and preventing unintended liberation or misalignment, however. The additional features increase the complexity of the core and spindle assembly, and correspondingly increase the cost. Cost is a significant factor in the manufacture and use of printer rolls, and must be minimized to maintain competitive advantage in the market of supplying replacement printing rolls.
Accordingly, it is desired to provide a simple, effective, low-cost replacement core for receiving wound sheet rolls and having corresponding retention features for mounting to a supporting spindle.